Product Description Package content: 1*filter 1. Extensive Compatibility Please measure the dimension of your fountain before purchase. Suitable for fountains from 2 to 2.5 liters particularly compatible with the fountain. Dimensions: outer diameter 125 mm inner diameter 37 mm thickness 10 mm. 2. 3-layer protection High tension cotton + activated carbon + ion exchange resin. Expel debris absorb heavy metals eliminate odors. Protect your little cat from unnecessary infections. Give them a healthier and tastier water juice! 3.Rinse and face up， Rinse the fountain filter for 10 minutes before use to remove charcoal dust. Please put the flat front face up to ensure the best filtration! 4. 2-4 week change Although our fountain filter can last a long time to ensure the best protective filtration for our animals we suggest changing every 2-4 weeks. With individual packaging each fountain filter can be easily stored and well reserved with the best effect!